Field of the Invention
The present disclosure relates to an organic light-emitting display (OLED) device, and more particularly to an OLED device with improved production yields and reliability by eliminating the possibility that a portion of an adhesive layer used for attaching an upper substrate to a lower substrate is not attached on the substrates in a bezel area.
Description of the Related Art
An organic light-emitting display device (OLED) is capable of producing light on its own and thus does not require an additional light source, as in a liquid crystal display device (LCD). Therefore, an OLED device can be made lighter and thinner. Further, an OLED device has advantages in that it is driven with low voltage to consume less power and realizes better colors. Also, an OLED device has a fast response time, a wide viewing angle and a high contrast ratio (CR). For these reasons, an OLED device is currently under development as the next generation display device.
FIG. 1 a schematic cross-sectional view of a plurality of OLED devices disposed between mother substrates in the related art. FIG. 1 shows a first OLED device PA1 and a second OLED device PA2 when a lower mother substrate 190 is attached to an upper mother substrate 195. Although two OLED devices (PA1 and PA2) are defined on the lower mother substrate 190 in FIG. 1 for convenience of illustration, the number of the OLED devices defined on the lower mother substrate 190 is not limited to two.
In the related art, an OLED device is manufactured in such a manner that a plurality of thin-film transistors 120, a plurality of organic light-emitting elements 140, etc., are disposed between the lower mother substrate 190 and the upper mother substrate 195. The lower mother substrate 190 is attached to the upper mother substrate 195, and then the mother substrates are divided into individual organic light-emitting devices.
Referring to FIG. 1, the plurality of thin-film transistors 120 are disposed in a display area DA of the lower mother substrate 190. A gate insulating layer 131, an interlayer insulating layer 132 and a planarization layer 133 are disposed in the display area DA during the manufacturing process of disposing the thin-film transistor 120.
The plurality of organic light-emitting elements 140 are disposed on the planarization layer 133. A bank layer 134 is disposed around the plurality of organic light-emitting elements 140. In a bezel area BA, a variety of lines 160 and/or circuitry necessary for driving the display area DA may be disposed. In the bezel area BA, ends of the planarization layer 133 and the bank layer 134 have a tapered shape. Further, there is a step difference between the bezel area BA and the display area DA, which is approximately equal to the sum of the thickness of the planarization layer 133 and the thickness of the bank layer 134.
In addition, an encapsulation layer 135 for protecting the organic light-emitting element 140 from moisture and oxygen is disposed on the organic light-emitting element 140. When a plurality of OLED devices are manufactured simultaneously by using a set of mother substrates, the position of a cut line CUT along which one OLED device is separated from another is determined between adjacent bezel areas BAs. In addition, a buffer region is disposed closely to the cut line CUT in the bezel area BA. The buffer region is configured to absorb physical impacts, such as shocks or vibrations, generated when the cut line CUT is cut by a cutter or a laser. Therefore, no conductive lines or circuitry are disposed in the buffer region.
The upper mother substrate 195 is attached to the lower mother substrate 190 by an adhesive layer 170. However, in the bezel area BA of each of the first OLED device PA1 and the second OLED device PA2, there exists an unwanted space due to the step difference. Accordingly, the adhesive layer 170 may not be sufficiently filled up in the unwanted space or may not be securely attached to the upper mother substrate 195 and/or the lower mother substrate 190 at the boundary between the bezel area BA of the first OLED device PA1 and the bezel area BA of the second OLED device PA2. As a result, a space S where the adhesive layer is not properly attached on the substrates may be created in the bezel areas BA as shown in FIG. 1.
Due to the space S (which is an unwanted space) created in the bezel areas BA when the upper mother substrate 195 is attached to the lower mother substrate 190, pressure applied to the cut line CUT may result in bending or vibrations on the upper mother substrate 195 and the lower mother substrate 190. Shocks or physical impact may occur at this time and may be delivered to the conductive lines 160 and/or the circuitry disposed in the bezel area BA. If such impacts are applied to the bezel area BA, cracks or other types of damage may occur in various components including a variety of lines and insulating layers. Once cracks or damage occur in one component, it can very easily lead to cracks or damage in other components. Even if no cracks occur during the process of attaching the adhesive layer 170, cracks or damage may occur during other processes of cutting the set of mother substrates into individual OLED devices, such as a process of laser cutting or a process of mechanical scribing, in which strong energy is exerted on the upper mother substrate 195. Therefore, crack may still occur in the lines 160 or other components.
In addition, in the existing manufacturing process of an OLED device according to the related art, an additional process may be performed after the set of mother substrates has been cut into individual OLED devices. For example, a process of attaching a polarizing plate or a process of applying a protective film onto the upper substrate or the lower substrate using a roller may be performed. During such processes, cracks may occur in the lines 160 or insulating layers due to generated pressure. In addition, pressure is exerted on the lower substrate during a process of attaching a polarizing plate, whereby cracks may occur in the lines 160 or the insulating layers. Accordingly, cracks occur in the line 160 or the insulating layers due to the space S created in the bezel area BA, deteriorating the production yields and reliability of an OLED device.
As described above, in the OLED device according to the related art, there exists the space S where the adhesive layer 170 is not attached on the lower substrate. Accordingly, the adhesive layer 170 and the lower substrate may peel off or otherwise not be attached properly, and the lower substrate may not be securely attached to the upper substrate. Therefore, delamination or process failure may be caused during subsequent processes. In addition, moisture or oxygen may permeate through the space S from a side surface of an OLED device, deteriorating the lifespan and reliability of the OLED device.